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• avutil/hwcontext_videotoolbox: BGRA should be full range

  3 January 2023, by Zhao Zhili

  avutil/hwcontext_videotoolbox: BGRA should be full range
  HEVC alpha layer encoding is broken without the patch.
  Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
  

  • [DH] libavutil/hwcontext_videotoolbox.c

• Format ffmpeg command to extract the full klv for an mpg/ts file

  24 December 2020, by Andrew Marquez

  I am extracting the KLV data from an mpg file using klvdata and ffmpeg.

  



  Following the readme, I have downloaded the sample "Day Flight.mpg" video file that contains KLV data. Running the quick start command works (I get the exact same result as the readme example for the first 6 frames.)

  



  However, for the life of me I don't know how I can extract the KLV data for the entire video file.

  



  As an experiment, I tried creating the KLV data file from an offset start:

  



  ffmpeg -ss 5 -i Day\ Flight.mpg -map data-re -codec copy -f data - > out.klv


  



  and when I run it through my code with different start times (5, 25, etc.) I do get different results.

  



  This (to me) would suggest that the mpg file does contain KLV data throughout, but I can only access 6 frames at a time.

  



  I would expect to be able to run an ffmpeg command to output the full KLV data. I need help formatting my ffmpeg command to properly provide all the data.

  



  To replicate, download the "Day Flight.mpg" file from the klvdata project page and run the command I posted above. You will note it is less than a page long. It should be many, many pages long. Thank you for your help!

  


• Use FFMPEG without downloading full file

  19 August 2020, by servalex

  I'm generating thumbnails for a videos that are available from s3 and need to minimize traffic.
Frame is going to be from the first couple seconds of the video so the question: is there a way to get frame without passing the full file through network?

  


  At the moment I'm passing video url to ffmpeg but seems like it downloads the whole file, not only first couple seconds.

  


  ffmpeg -ss 0 -noaccurate_seek -i {srcPresignedUrl} -vframes 1 -q:v 2 {outputFileName}

  


  I tried downloading first 10mb of the file and passing it, this works for some mp4 files, but fails on mov:

  


  ffmpeg.exe -ss 0 -i source.mov -vframes 1 -q:v 2 thumb.jpg
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 10.2.1 (GCC) 20200726
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libgsm --enable-librav1e --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0000017582ffff40] moov atom not found
source.mov: Invalid data found when processing input